A new crash test from the Insurance Institute for Highway Safety is turning out to be a difficult hurdle for some car makers whose models had previously won top honors in the safety group’s evaluations with apparent ease.

In a recent test session models from Toyota failed to make the list of cars winning the Top Safety Pick + award from the IIHS, a safety-testing organization funded by the insurance industry. In the past the brand had been a regular winner but this time its Camry and Prius v models received “poor” ratings in the small-overlap frontal crash test, which focuses the power of a collision on parts of a vehicle that tend to be relatively weak.

In the group of 18 midsize family cars tested, 13 made the top-rated list. The “plus” sign in the Top Safety Pick + designation means the vehicle gets a good or acceptable rating in the small-overlap test while receiving the top “good” rating in the milder IIHS offset frontal-, side-, and rear-impact, and roof-strength tests.

Of the cars tested in the latest round, only the Honda Accord and Suzuki Kizashi received good ratings in the new test.

The latest testing so far indicates that modestly priced family cars perform better in the demanding small-overlap test than costlier, more luxurious models. Just three of 11 midsize luxury and near-luxury cars recently tested received good or acceptable ratings.

“It’s remarkable that this group of midsize family cars did so much better than the midsize luxury car group,” says Adrian Lund, IIHS president. “The difference is stunning,” he said.

IIHS rolled out the small-overlap test in 2012 further challenge car companies whose latest vehicles were nearly always receiving top marks. Most auto makers for years have designed and engineered their vehicles specifically to perform well in the IIHS tests, but many have not focused on the small overlap test, which replicates the effects of a collision between the front corner of a car and another vehicle or narrow obstacles like trees and utility poles. In the test, 25% of a car’s front end on the driver side strikes a 5-foot-tall rigid barrier at 40 mph.

In a 2009 study the IIHS found that among vehicles with good ratings for frontal crash protection, small overlap crashes accounted for almost 25% of the frontal crashes with serious or fatal injuries to front- seat occupants.

Most modern cars are designed around safety cages that protect occupants and crush zones that absorb or otherwise direct crash energy away from passengers. But the main impact-absorbing structures are in the middle 50% of the vehicle’s front end, IIHS said.

In many vehicles a 25% overlap frontal crash misses the primary structures designed to manage the forces of impact. As a result the force is directed toward the wheel, suspension system and other parts that can be forced into the passenger compartment. This type of crash is also especially dangerous because of the car’s tendency to rotate on impact, forcing the driver’s head outward, away from the front airbag.